气候变化领域集成服务门户(CCPortal): Upper plate deformation and trench retreat modulated by subduction-driven shallow asthenospheric flows

CCPortal

DOI	10.1016/j.epsl.2019.116013
	Upper plate deformation and trench retreat modulated by subduction-driven shallow asthenospheric flows
	Alsaif M.; Garel F.; Gueydan F.; Davies D.R.
发表日期	2020
ISSN	0012821X
卷号	532
英文摘要	Upper plate deformation within a subduction zone depends on the complex relationship between surface plate motions, trench motion, slab pull and asthenospheric flow. Previous modelling studies suggest that trench motion rates should be related to slab buoyancy, but this relationship is neither clear nor verified by observations of natural subduction systems. Trench motion is also thought to induce upper plate deformation; however, no clear correlation has been identified between the direction of trench motion and the mode of upper plate deformation. In this study, we construct 2-D thermo-mechanical models to explore the relationship between slab pull, trench retreat and upper plate deformation, focusing on subduction systems with retreating trenches. We start with quasi-steady-state subduction and introduce a positive density anomaly into the slab to transiently increase slab pull. We vary both the value of the density anomaly and the properties of the upper plate to isolate key controls on trench retreat and upper plate deformation. Our models indicate that asthenospheric flow responds to changes in slab pull and influences both trench retreat and upper plate deformation. We propose that trench retreat depends on the competition between shallow and opposite asthenospheric flows below the subducting and upper plates, and that a fast sub-slab flow can hamper trench retreat even when slab buoyancy is high. After a transient slab pull increase, the mode of upper plate deformation partly depends on the upper plate's ability to translate horizontally: an upper plate with a ridge at its trailing edge deforms by shortening, while a fixed upper plate may deform by extension. Finally, in some cases, upper plate deformation seems to allow trench retreat if the upper plate is weak enough to be deformed by the basal shear from underlying asthenospheric flow. Our results provide insights into retreating subduction systems with contrasting upper plate deformation modes, such as the compressive Andes and the extensional Aegean. © 2019 Elsevier B.V.
关键词	asthenospheric mantle flow numerical modelling slab rollback subduction trench retreat upper plate deformation
英文关键词	Buoyancy; Numerical models; Shear flow; Asthenospheric flow; Complex relationships; Mantle flow; Quasi-steady state; slab rollback; subduction; Thermomechanical model; Upper plate; Deformation; asthenosphere; deformation; mantle convection; numerical model; plate motion; slab; subduction zone; trench; Andes
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202469
作者单位	Géosciences Montpellier, Université de Montpellier, CNRS, Montpellier, France; Research School of Earth Sciences, The Australian National University, Canberra, Australia
推荐引用方式 GB/T 7714	Alsaif M.,Garel F.,Gueydan F.,et al. Upper plate deformation and trench retreat modulated by subduction-driven shallow asthenospheric flows[J],2020,532.
APA	Alsaif M.,Garel F.,Gueydan F.,&Davies D.R..(2020).Upper plate deformation and trench retreat modulated by subduction-driven shallow asthenospheric flows.Earth and Planetary Science Letters,532.
MLA	Alsaif M.,et al."Upper plate deformation and trench retreat modulated by subduction-driven shallow asthenospheric flows".Earth and Planetary Science Letters 532(2020).